Oscillation is widely utilized for this type of piece feeder while some use a rotating mechanism to reduce vibration. But both have the following problems.
Conventional Vibration Types:
    1) They make loud noise because of vibration to deteriorate working environment.    2) The bowls are easily worn down by abrasion. Thus, the running cost rises    3) Feeding speed of the pieces vary according to the fluctuation of the power voltage.    4) They are not economical because they consume much electricity to operate.Conventional Rotating Type:    5) The initial and running cost is expensive because the structure is complicated and difficult to operate and maintain.    6) A piece has to travel a long distance because the apparatus sends the pieces by inclined rotation.    7) The variety of pieces is limited because the structure confines its versatility